African American women contract HIV, and other sexually transmitted and blood borne pathogens, at an unacceptably high rate, despite 15 years of prevention efforts. The continued spread of HIV among women suggests that individual level HIV preventive interventions may not be sufficient to stem the tide of infection among women. One hundred sixty African American women, aged 16 to 40, who used injected or non-injected cocaine, crack and/or heroin in the past 30 days will be street recruited in Bedford Stuyvesant, New York City, a high AIDS prevalence neighborhood, and followed for 18 months at six month intervals. Index women will nominate and assist in recruiting their current drug use and sex risk network members into the study at each interview. The baseline sample 640 subjects will consist of 160 index women and 480 risk network members. We propose to examine the relationships among socioeconomic factors, egocentric risk networks, individual risk behaviors, and the risk of infection. The five specific aims are: (1) establish the baseline seroprevalence of HIV, Hepatitis C (HCV), Hepatitis B (HBV), and syphilis, and the baseline seroincidence of HIV, among index women and their risk network members; (2) describe index women's resource acquisition strategies and the relationship of these strategies to egocentric risk network variables, individual risk behaviors, and infection; (3) assess the seroincidence among index women, as well as changes in the seroprevalence and/or seroincidence among women's egocentric risk network members, of HIV, HCV, HBV and syphilis over time, and the resource, risk network, and behavioral factors that predict incident infection; (4) ascertain changes in index women's egocentric risk networks over time that increase or decrease the risk of exposure to infection and/or participation in risk behaviors, and the relationship of network changes to women's resource acquisition strategies; and (5) using qualitative methods, explore the events, situations or actions that result in changes in network membership. The findings from this study should provide preliminary evidence as to the feasibility of implementing network preventive interventions among women who use drugs.